I have a professionally installed 6kW grid-tie inverter with 24 solar panels, which brought in about 8 MWh for the whole year in 2017. I live in the greater Chicago area, USA.

I have a net metering contract with the electric company, which allows to get credit (not paid) for electricity sent to the grid.

I use about 13 MWh annually, but I am still a net user of electricity. Most of this electricity goes to my two PHEV (plug-in hybrid electric vehicles), which together use about 5-6 MWh annually.

I also have hourly pricing on electricity, so the prices of electricity can surge to over $0.20 per kWh during the evening (around 5pm local time) when people get home from work or drop down to negative values during times of low demand.

As part of my hourly pricing, I have a capacity charge which "represents the amount of power generation capacity that is needed during peak demand times, which typically occur in the afternoon on hot summer days." This capacity charge adds about $20 each month to my bill, which makes it hard to lower my bill with hourly pricing.

2. Plan for the powerwall

It comes down to better control of electrical usage. When electricity costs are high, I want to use electricity from the powerwall. When the solar panels are generating excess electricity or electricity is cheap (or even negative), I want to charge the powerwall.

3. My background

I mostly a theorist with limited practical hand skills, but do some work in a chemistry lab. My day is job is a combination of teaching at the graduate school level and software development. I have degrees in math, physics, and biochemistry. So, I am great at the calculations and theory, but I am not a craftsman because the quality of my work is less than refined.

Other hobbies include: Linux home automation (beyond light bulbs and outlets). I have been a cryptocurrency enthusiast since summer 2014, so I have have a solid understanding of cryptocurrency and would be happy to shill for Dash.

4. My powerwall, so far...

Started seriously gathering in October 2017, I have gathered and capacity tested 255 18650 batteries (Opus method) of which about 100 that still need to be long-term voltage tested. Plan to buy a Batrium, once I get enough batteries. Shooting for a 14s80p (1120 batteries) or 14s100p if I can get enough batteries. Need to find a large scale recycler to get more cells.